Cedar, I am getting over "the win." The win for the sister is thinking sh e has the control. She has the last word. She can stop me from doing something, even if she calls the cops. If that is her idea of a win, let her win. Although she can't stop me from doing anything anymore as she is not a part of my life and that makes her input insignificant.
If she thinks sh e is the winner, then let it be. Why should I care?